Low threading dislocation density relaxed mismatched epilayers without high temperature growth

Abstract

A semiconductor structure and method of processing same including a substrate, a lattice-mismatched first layer deposited on the substrate and annealed at a temperature greater than 100° C. above the deposition temperature, and a second layer deposited on the first layer with a greater lattice mismatch to the substrate than the first semiconductor layer. In another embodiment there is provided a semiconductor graded composition layer structure on a semiconductor substrate and a method of processing same including a semiconductor substrate, a first semiconductor layer having a series of lattice-mismatched semiconductor layers deposited on the substrate and annealed at a temperature greater than 100° C. above the deposition temperature, a second semiconductor layer deposited on the first semiconductor layer with a greater lattice mismatch to the substrate than the first semiconductor layer, and annealed at a temperature greater than 100° C. above the deposition temperature of the second semiconductor layer.

Description

BACKGROUND OF THE INVENTIONThe invention relates to the field of low threading dislocation density relaxed mismatched epilayers, and in particular to such epilayers grown without high temperature.The goal of combining different materials on a common substrate is desirable for a variety of integrated systems. Specifically, it has been a long-standing desire to combine different semiconductor and oxide materials on a common useful substrate such as a silicon substrate. However, just as the different materials properties are beneficial from the system application perspective, other properties may make such materials combinations problematic in processing. For example, semiconductor materials with different properties often have different lattice constants. Therefore, upon deposition of one semiconductor material on top of another substrate material can result in many defects in the semiconductor layer, rendering it useless for practical application.Seminal work into the quantitative in...

AI Technical Summary

Benefits of technology

The problems of the prior art can be overcome by developing a method to create high dislocation velocities even though deposition occurs at lower growth temperatures. Accordingly, the invention provides a structure and a method to produce a low threading dislocation density, mismatched epilayer without the need for depositing the film at high temperature, thus avoiding the germane particle generation.

Problems solved by technology

However, just as the different materials properties are beneficial from the system application perspective, other properties may make such materials combinations problematic in processing.

Therefore, upon deposition of one semiconductor material on top of another substrate material can result in many defects in the semiconductor layer, rendering it useless for practical application.

However, practical constraints from current equipment used to manufacture Si-based epitaxial layers create difficulty in depositing high germanium concentration alloys without deleterious particle formation from either gas phase nucleation or equipment coating.

Although these systems offer great control of Si epilayer thickness uniformity across a wafer, the process encounters problems when germane is added to the gas stream to deposit SiGe alloy layers.

The overall effect is that the epitaxial growth on the Si wafer can incorporate many particles, which not only degrade material quality locally, but also act as heterogeneous nucleation sites for additional threading dislocations, decreasing overall material quality.

Particle generation occurs more rapidly with higher growth temperature; thus, the growth conditions that lead to lower threading dislocation densities (i.e. higher growth temperatures), unfortunately lead to more particles and a higher threading dislocation density than expected.

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